cosmic rays

cosmic rays
/kɒzmɪk ˈreɪz/ (say kozmik 'rayz)

plural noun
radiation of extremely high penetrating power originating from various sources outside the earth's atmosphere, consisting principally of charged particles moving at nearly the velocity of light. Low-energy cosmic rays emanate from the sun, but the source of high-energy extragalactic cosmic rays is not known.
Also, cosmic radiation.

Australian English dictionary. 2014.